When optical microscopy meets all-optical analog computing:A brief review

As a revolutionary observation tool in life science,biomedical,and material science,optical microscopy allows imaging of samples with high spatial resolution and a wide field of view.However,conventional microscopy methods are limited to single imaging and cannot accomplish real-time image processing.The edge detection,image enhancement and phase visualization schemes have attracted great interest with the rapid development of optical analog computing.The two main physical mechanisms that enable optical analog computing originate from two geometric phases:the spin-redirection Rytov-Vlasimirskii-Berry(RVB)phase and the Pancharatnam-Berry(PB)phase.Here,we review the basic principles and recent research progress of the RVB phase and PB phase based optical differentiators.Then we focus on the innovative and emerging applications of optical analog computing in microscopic imaging.Optical analog computing is accelerating the transformation of information processing from classical imaging to quantum techniques.Its intersection with optical microscopy opens opportunities for the development of versatile and compact optical microscopy systems.

Photonic spin Hall effect:fundamentals and emergent applications

The photonic spin Hall effect(SHE)refers to the transverse spin separation of photons with opposite spin angular momentum,after the beam passes through an optical interface or inhomogeneous medium,manifested as the spin-dependent splitting.It can be considered as an analogue of the SHE in electronic systems:the light’s right-circularly polarized and left-circularly polarized components play the role of the spin-up and spin-down electrons,and the refractive index gradient replaces the electronic potential gradient.Remarkably,the photonic SHE originates from the spin-orbit interaction of the photons and is mainly attributed to two different geometric phases,i.e.,the spin-redirection Rytov-Vlasimirskii-Berry in momentum space and the Pancharatnam-Berry phase in Stokes parameter space.The unique properties of the photonic SHE and its powerful ability to manipulate the photon spin,gradually,make it a useful tool in precision metrology,analog optical computing and quantum imaging,etc.In this review,we provide a brief framework to describe the fundamentals and advances of photonic SHE,and give an overview on the emergent applications of this phenomenon in different scenes.